A conventional hand tool such as a wrench generally includes a head and a handle wherein the head includes driving member or an engaging hole so as to be connected with an object to be tightened or loosened. The user holds and rotates the handle so as to output a torque to the object. However, the head is fixed to the handle so that the head cannot reach an object that is located in a narrow space or at an angle to a surface where the wrench can normally reach. U.S. Pat. No. 5,842,391 discloses a pivotable head of a wrench, however, the range of angles that the head can be pivoted is limited and cannot meet practical needs. U.S. Pat. No. 6,928,904 discloses a pivotable head which is connected to the handle by a pivoting device. The pivoting device includes a complicated structure and occupies a large space such that the connection portion of the handle and the head is so big that it cannot inserted into a narrow space.
The present invention intends to provide a pivoting device for hand tools wherein the head can be pivoted within a range from positive 90 degrees to negative 90 degrees, and the head can be well secured at adjusted angles.